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AM3354: TSC ADC control

shigehiro tsuda
Mastermind 9490 points
Part Number: AM3354

Hi,

Which is the correct control of TSC ADC of AM335x?
① The Touchscreen sample of the starterware uses both FIFO0 and FIFO1, and it reads data of FIFO0 and FIFO1 at the event of FIFO1 threshold. Therefore, only the FIFO1_TR interrupt is enabled.
② TSC ADC driver for Linux uses only FIFO0 and reads the data of FIFO0 with the event of FIFO0 threshhold. In addition to FIFO1_TR, EOS interrupt is enabled.
It seems that it is only waiting as EOS processing.

Our customers are based on ①, but there is a problem that the FSM busy will remain "1".
Is there any information as the correct sequence?

Best Regards,
Shigehiro Tsuda

  • 0
    TI__Guru**** 393215 points
    Hi,

    In what situations does FSM remain busy?
  • 0 in reply to Biser Gatchev-XID
    Mastermind 9490 points

    Hi Biser,

    Thank you for quick reply.
    When the touch panel is kept pressed, the FSM remains busy and the ADC hangs.
    I'm investigating whether the sequence is correct.
    Is there any information as the correct sequence?

    Best Regards,
    Shigehiro Tsuda

  • 0 in reply to shigehiro tsuda
    TI__Guru 62855 points
    A few customers have experienced a condition where the busy bit gets set and the ADC is permanently locked. This condition seems to be related to energy from ESD events created when people touch the screen. The energy is being transfer into the processor and causing the ADC to hang. When this occurs the only way to clear the condition is to reset the processor.

    If this is what is happening, a filter and/or voltage clamps will need to be inserted on the ADC inputs to block this energy from being coupled into the processor.

    Regards,
    Paul
  • 0 in reply to peaves
    Mastermind 9490 points
    Hi Paul,

    Thank you for quick reply and answer.
    I understand that it may be caused by ESD when touching the touch screen.
    Please let me know if there is a corresponding circuit recommended by the TSC_ADC circuit with a filter and/or voltage clamps .

    Best Regards,
    Shigehiro Tsuda